[HCBPH]

Just returned from a LA to Mpls run (1938 miles), picking up a 07 SCab XLT. Not the most popular combo but it fits with my needs (Personal and my business), plus I had been looking for months for the right one and this was the closest match.
07 XLT SCab LB 4x2. 5.4L auto, 8200 GVW, 4.10 posi with towing package, 20K miles. It will spend about 90% of it's time in town so it seems the best match for my needs.
Truck didn't have a full tank when I picked it up and couldn't find a gas station before the interstate so I did my mileage calculations from the first fillup through the end of the trip. I tried to run cruise as much as safely possible, kept the speed at 68 mph (2200 rpms) or speed limit whichever was lower as much as possible. I didn't run the AC the entire trip and kept 2 windows open for ventilation I did run into alot of road construction the entire way, so I didn't run cruise as much as I'd have liked. I also tried using different brands of gas to see if that made a difference. Each stop, filled it till the pump shut off, then went up to the next nickel and quit filling. Trip was LA - Vegas - Denver - Omaha - Des Moines - Minneapolis (as much interstate as possible). That's the setup on the trip and here's the results: Average mpg: 17.6, Best: 19.38, Worst: 16.02. In all fairness the worst was when I tried some high alcohol blend, truck didn't like that. Best Brand: Seems to like BP better than the others I tried.
Nothing scientific here, just recorded the fuel pumped and mileage between fills.
Truck never missed a beat but did have some heartpounding events. Less than 10 miles after buying it, got hit by a thrown truck tread on I10 in LA. Nowhere to go and it got me. tore up the license and lower bumper plastic. It did take the 113 degree desert temp (based on dash reading) without overheating though I didn't run AC. Only downshifted a couple of times while in cruise in climbing the mountains (where I could safely run cruise). Didn't lose much if any speed climbing the mountains. Overall a long but productive test.

Hope someone finds this useful.

Paul